Generally, a blade used by gas turbines, blowers, or the like is configured so as to be surrounded by: a leading edge portion, which is where the fluid flows in; a pressure surface which is a concave curve shape concaved along a direction the fluid flows; a suction surface which is a convex curve shape convexed along a direction the fluid flows; and a trailing edge portion, which is where the fluid flows out. Conventionally, as shown in Japanese Unexamined Patent Applications, First Publication Nos, 2002-21502 and 2000-104501, for example, improvement of efficiency, performance, or blowing performance of turbines has been intended or generation of noise has been prevented by preventing a boundary layer of the fluid flowing on the suction surface from separating at the trailing edge portion. This is known as a laminar separation.
Here, in a case in which the blade is used under a high altitude condition, such as in an aircraft engine, the above-described laminar separation easily occurs since the Reynolds number decreases at the trailing edge portion of the suction surface.